# Regular Faculty

**Title**- Professor
- Graduate Vice Chair

**Division**Physical & Biological Sciences Division**Department**- Mathematics Department

**Phone**831-459-5001**Email****Fax**831-459-4511**Website****Office Location**- McHenry Library, McHenry Building Room #4190

**Mail Stop**Mathematics Department**Mailing Address**- 1156 High Street
- Santa Cruz CA 95064

### Research Interests

Robert Boltje’s research centers around the theory of finite groups, their representations, and applications to algebraic number theory. Within the theory of finite group representations he has been working on natural induction formulae for many years. A very useful tool in this theory is the language of Mackey functors. This structure occurs surprisingly often in different fields of mathematics when group actions on mathematical objects (sets, vector spaces, topological spaces, fibre bundles) are present. Also, the presence of a Mackey functor structure on the ideal class groups of number fields in a fixed Galois extension provides relations between these class groups. The ideal class group is an invariant which measures how close the ring of integers in a number field is to having unique factorization into primes.

Presently, Robert Boltje is interested in the conjectures of Alperin, Dade, and Broué in the representation theory of finite groups. These conjectures link blocks of representations of a finite group G to blocks of representations of various subgroups arising as normalizers of chains of p-subgroups of G. It seems that the topology of the simplicial complex of p-subgroups together with its G-action plays an important role, and that ideas from other fields of mathematics like geometry or algebraic topology are needed to prove the conjectures.

### Biography, Education and Training

Professor of Mathematics

Dr. rer. nat. habil., University of Augsburg

Ph.D., University of Augsburg

### Selected Publications

- R. Boltje: A general theory of canonical induction formulae, J. Algebra (1998), 293-343.
- R. Boltje: Linear source modules and trivial source modules, Proc. Sympos. Pur Math. 63 (1998), 7-30.
- R. Boltje: Class groups relations from Burnside ring idempotents, J. Number Theory (66)(1997),291-305
- R. Boltje: Identities in representation theory via chain complexes, J. Algebra 167 (1994), 417-447.
- R. Boltje: A canonical Brauer induction formula, Astérisque 181-182 (1990), 31-59.